Boost problems

[wormfooduk]

This is the boost ive just built, its my first layout of a SHO style boost. I think its almost the same. I can't get rid of a pop when switching. Could it be the caps or the resister value of the resister to ground from the output cap. Any ideas welcome.

[Archer18]

I put a 1m resistor between the input and input cap which goes straight to ground

[Al Heeley]

I think the recommendation on AMZ FX (Muzique.com) is to put a cap in next to the LED so the current surge is slowed.
http://www.muzique.com/lab/led.htm
I have also heard a 2m resistor across the tip and sleeve of the input jack can help reduce the pop, this should acheive same as above post.

[earthtonesaudio]

I have also heard a 2m resistor across the tip and sleeve of the input jack can help reduce the pop, this should acheive same as above post.

This won't work.  The resistor needs to go from the cap to ground on the *circuit side* of the switch, not the *bypass side*.  Putting it on the bypass side not only doesn't stop popping, but also loads the guitar down all the time, defeating the purpose of true bypass.

[wormfooduk]

Thanks for the replies, It didn't seam to help, i tried droping the value of the output to ground resister and it is maybe a bit better still there though.   Ive also taken the LED out of the circuit to make sure it wasnt that.

[MikeH]

I have also heard a 2m resistor across the tip and sleeve of the input jack can help reduce the pop, this should acheive same as above post.

This won't work.  The resistor needs to go from the cap to ground on the *circuit side* of the switch, not the *bypass side*.  Putting it on the bypass side not only doesn't stop popping, but also loads the guitar down all the time, defeating the purpose of true bypass.

A lot of people confuse this with curing popping in a true bypass loop.  In that case the 1M etc resistor should be put across the send and/or return jack from tip to sleeve.  This is to drain the input/output caps in the pedals that are in the loop.  But like earthtone said, it wont work on input and output jacks.

[Al Heeley]

OK sonow I'm confused about best way to sort this - some of my pedal builds seem to have quite loud pop when they are connected to the mains but battery powered popping is less of an issue.

[MikeH]

Could be due to the current draw of your LED

[wormfooduk]

Still have the problem with my boost, ive not got a LED anymore and the pop is still there.

[earthtonesaudio]

Still have the problem with my boost, ive not got a LED anymore and the pop is still there.

First make sure you've wired your switch correctly.  Then measure DC voltages on input and output when effect is on vs. off.  They should be the same. 


After all that, if this does not cure it:

I put a 1m resistor between the input and input cap which goes straight to ground

...I would start to suspect a faulty switch.

[wormfooduk]

I don't think its the switch, how much heat does it take to damage a switch? Its really bugging me now i've tried everything i can think of so i guess it does just leave the switch.

[ayayay!]

how much heat does it take to damage a switch?

Surprisingly very little for a standard 3PDT.  Actually it's not so much the heat as the time taking to apply said heat.  You've gotta be quick:  in and out soldering for those 3PDTs, and they don't care much for do-overs. 

I do think this sounds like a switch.  I once got a batch of about 4 out 5 that were bad from the get go.  Before that I preached religiously that those switches were just fine out of the starting blocks. 

[petemoore]

The DC blocking [input/output] caps may store charge, when switched [bypass switch throws are thrown], the caps get connected to out of box items, if there's a charge in the capacitor[s, it gets 'sparked' or otherwise quickly discharges..into the signal path.
  Put a big resistor there and drain all DC capacitor charges to ground.
  ..outside the cap/inside the bypass switch, see schematics which have these large capacitor pulldown resistors at input/output for examples.
  Very rarely <470k, 1 meg generally, maybe more, small values drain faster and may load signal for same reason...
  I've never had too many troubles. Nor have I reduced pulldown resistor values and gotten any mileage reducing pops either, so my tendancy is to lean toward 'it's something else' besides the pulldown resistor values.

[wormfooduk]

I will try changing the switch first, i didnt know they were easy to damage, but hay i do now 

if its not the switch i will play with the pull down resister values.

[earthtonesaudio]

I will try changing the switch first, i didnt know they were easy to damage, but hay i do now 

if its not the switch i will play with the pull down resister values.

If you start swapping parts before you do these suggested steps (in order)...

First make sure you've wired your switch correctly.  Then measure DC voltages on input and output when effect is on vs. off.  They should be the same. 


After all that, if this does not cure it:

I put a 1m resistor between the input and input cap which goes straight to ground

...I would start to suspect a faulty switch.

...you may fix the problem.  In which case, great!  Or, you may not fix the problem.  In that case, you've used up another switch and you don't even know if that was the problem in the first place.  Worse, you may introduce another unrelated problem by giving yourself the opportunity to make a mistake.

I would recommend testing for leakage before changing any parts.

[wormfooduk]

Ok a bit late reading this, but the good news is it seams to be the switch. I stuck some clips on a spare 3pdt switch and just clipped the wires to it and now i have no noise when switching at all. Im now worried about soldiering switchs

Anyway thanks for your help guys. I now know what to look for if the pops arnt coming from the switch next time.